how to set background of the color map with shape file/image in hand

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Muhammad Usman Saleem 2015-7-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/230393-how-to-set-background-of-the-color-map-with-shape-file-image-in-hand

评论： Priyank Pathak 2022-9-19

Hi every one; I want to make color map from text file which contains three columns( 1st is latitude, 2nd is longitude, 3rd is temperature). I have accessed to this code which reading and creating color map from text file(1-1000.text)

fid = fopen('1-1000.txt');
 C = textscan(fid, '%f %f %f')
 fclose(fid);
 f = {'lat', 'long', 'temp'}
 S = cell2struct(C,f,2);
   N = 1000;
   [Xi, Yi] = meshgrid(linspace(60,80,N),linspace(20,40,N));
   Ci = griddata(S.long, S.lat, S.temp, Xi, Yi);
   colormap ('hot')
   imagesc(linspace(60,80,N),linspace(20,40,N),Ci);
   xlabel('Longitude');
   ylabel('Latitude');
   colorbar

it has output

The data in text file represent region , i have shape file of that region i want to set this region as the background of this color map. I have attached with this post text data, my requried output map and shape file of the region. Please set my code so that background of the map will become region of my shapefile. Thanks in advance for assistance. Regards

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Walter Roberson 2015-7-24

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Muhammad Usman Saleem 2015-7-24

@Walter thanks for your contributions. Please vote up if my question was interesting :)

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采纳的回答

Amy Haskins 2015-7-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/230393-how-to-set-background-of-the-color-map-with-shape-file-image-in-hand#answer_186731

在 MATLAB Online 中打开

Once you've gotten your data into a regular grid of latitudes and longitudes as you've done above, the geoshow function in the Mapping Toolbox can help with the rest.

First use geoshow to get your surface plot into a map axes. If you don't already have a map open, geoshow will create a default one. If you would perfer a different projection, take a look at the doc for axesm.

h = geoshow(Yi,Xi,Ci,'DisplayType','surface');

This creates an actual surface plot, but you're after a 2D map, so let's flatten out the ZData.

h.ZData = zeros(size(h.XData));

Your shape file contains polygons. You have a couple of options here. I think it looks nice to overlay just the edge lines, but you could play with the transparency and fill in the polygons.

 p = geoshow('pakistanshapefile\PAK_adm1.shp', ...
             'DisplayType','polygon','FaceColor','none','EdgeColor','w')

 p = geoshow('pakistanshapefile\PAK_adm1.shp',...
             'DisplayType','polygon','FaceAlpha',0.25)

Alternately, you could move the polygons to the bottom using uistack(p,'bottom') and change the FaceAlpha property of the surface if you really want the shape file in the background.

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Muhammad Usman Saleem 2015-7-21

编辑：Muhammad Usman Saleem 2015-7-21

在 MATLAB Online 中打开

@Amy Haskins thank you very much for contributions. I make what i understand from you answer

fid = fopen('1-1000.txt');
 C = textscan(fid, '%f %f %f')
 fclose(fid);
 f = {'lat', 'long', 'temp'}
 S = cell2struct(C,f,2);
     N = 1000;
     [Xi, Yi] = meshgrid(linspace(60,80,N),linspace(20,40,N));
     Ci = griddata(S.long, S.lat, S.temp, Xi, Yi);
     colormap ('hot')
     imagesc(linspace(60,80,N),linspace(20,40,N),Ci);
     xlabel('Longitude');
     ylabel('Latitude');
     colorbar
     h = geoshow(Yi,Xi,Ci,'DisplayType','surface');
      h.ZData = zeros(size(h.XData));
      p = geoshow('pakistanshapefile\PAK_adm1.shp', ...
               'DisplayType','polygon','FaceColor','none','EdgeColor','w')
           uistack(p,'bottom')

It has output, lines on image is actually matlab to png conversion

i am getting this error also

C = 
      [323x1 double]    [323x1 double]    [323x1 double]
f = 
      'lat'    'long'    'temp'
??? Attempt to reference field of non-structure array.

Please see that in image x,y are wrong in number and also no background polygon is set? please correct these codes . I shall be very thankful to you on this favor.

Muhammad Usman Saleem 2015-7-21

@Amy Haskins thanks for your kind contributions.Please see my reply to @Nitin Khola in the above answer(last two reply)? How can i resolve that problem. Thanks in advance for your kind contributions.

Muhammad Usman Saleem 2015-7-24

编辑：Muhammad Usman Saleem 2015-7-24

@Amy Haskins thank you very much for resolving this problem :) Please vote up my question

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更多回答（1 个）

Nitin Khola 2015-7-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/230393-how-to-set-background-of-the-color-map-with-shape-file-image-in-hand#answer_186739

在 MATLAB Online 中打开

As per my understanding, you wish to set the background of the given colormap to a map outline imported from a shapefile. I am assuming you have a license for the MAPPING TOOLBOX and are using MATLAB R2015a. To achieve it, as per this assumption, you can use the function "shaperead":

http://www.mathworks.com/help/map/ref/shaperead.html

to import the shapefile and then overlay the given colormap on a plot of data from the shapefile. The transparency of the colormap can be changed using "alpha" command so that the outline is visible. I was able to do it using the following code:

im = shaperead('PAK_adm1.shp'); % import the shapefile
plot([im.X],[im.Y],'k','LineWidth',2.0); % plot X,Y data
hold on;
fid = fopen('1-1000.txt');
C = textscan(fid, '%f %f %f');
fclose(fid);
f = {'lat', 'long', 'temp'};
S = cell2struct(C,f,2);
N = 1000;
[Xi, Yi] = meshgrid(linspace(60,80,N),linspace(20,40,N));
Ci = griddata(S.long, S.lat, S.temp, Xi, Yi);
colormap ('hot')
imagesc(linspace(60,80,N),linspace(20,40,N),Ci);
xlabel('Longitude');
ylabel('Latitude');
colorbar
alpha(0.85) % Change transparency of the colormap so that map is visible

You might want to change some of the values in the above code as per your needs.

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Muhammad Usman Saleem 2015-7-21

编辑：Muhammad Usman Saleem 2015-7-21

PAK_adm1.jpg

Again thanks @Nitin Khola for your kind contributions. I want to adjust some little more

There is white region which is free from data frame. I want to show only data frame not white space?
Please see the boundary line its format has distortions. I want your suggestions if we use jpg/ tiff image of PAK_admin instead of shapefile , will the boundary edges improve in format? Please test this i have attached jpg image of PAK_admin

3. I want to makes these maps as shown in the sample_map.jpeg (i have attached this) , this consist on 36 maps , three represent for each months

4. I want your suggestion , i have missing values of temperature in text file.I have put them as 0 values. What about the idea if i replace 0 values with NaN(Not A Number) values. In making map we adjust our code such that in map where NaN values occur there no raster surface created( In this way i can tell the user of my map white color show missing data for that geographic region). Please see my sample_map(white color on it shows missing data)?